ObjectModel service

Python client examples for the ObjectModel gRPC service.

See ObjectModel for this service’s complete reference material.

Python

import grpc
from ansys.api.fluent.v1 import object_model_pb2, object_model_pb2_grpc
from ansys.api.fluent.v1 import variant_pb2

channel = grpc.insecure_channel("<server-address>")
metadata = [("password", "<password>")]
stub = object_model_pb2_grpc.ObjectModelStub(channel)

The rules string selects the application context. All examples on this page use "meshing".

Discovering the schema

GetSchema returns the static tree of objects, commands, queries, and parameters — walk it to discover valid paths before making runtime calls.

Python

schema_response = stub.GetSchema(
    object_model_pb2.GetSchemaRequest(rules="meshing"),
    metadata=metadata,
)

def walk(node, indent=0):
    prefix = "  " * indent
    for name, child in node.singletons.items():
        print(f"{prefix}{name}/")
        walk(child, indent + 1)
    for name, child in node.named_objects.items():
        print(f"{prefix}{name}:<name>/")
        walk(child, indent + 1)
    for name in node.parameters:
        print(f"{prefix}{name}")
    for name in node.commands:
        print(f"{prefix}{name}()")

walk(schema_response.info)

Schema output (click to expand)

File/
  StartJournal()
  StopJournal()
  WriteCase()
  ReadCase()
  ReadMesh()
  ... (2 more commands)
Graphics/
  Bounds/
    BoundZ
    BoundX
    BoundY
    Selection
    DeltaValue
    ResetBounds()
    SetBounds()
  Regions/
    DrawDead()
    DrawAll()
    DrawFluid()
    DrawSolid()
  MarkGaps()
  ClippingPlane()
  DrawThinVolumeRegions()
  GetClippingZoneIDs()
  GetVisibleDomainBounds()
GlobalSettings/
  FTMRegionData/
    AllRegionTypeList
    AllRegionMeshMethodList
    AllRegionOversetComponenList
    AllOversetVolumeFillList
    AllRegionSizeList
    ... (9 more parameters)
  LengthUnit
  EnableCleanCAD
  EnableOversetMeshing
  UseAllowedValues
  EnablePrimeMeshing
  ... (9 more parameters)
Diagnostics/
  Draw()
  List()
  Previous()
  Next()
  Ignore()
  ... (9 more commands)
AddShellBoundaryLayerControls()
SizeControlsTable()
IdentifyDeviatedFaces()
IdentifyConstructionSurfaces()
CreateBackgroundMesh()
... (78 more commands)

Reading and writing state

Python

# Fetch a current boolean value.
state_response = stub.GetState(
    object_model_pb2.GetStateRequest(
        rules="meshing",
        path="/GlobalSettings/EnableCleanCAD",
    ),
    metadata=metadata,
)
current = state_response.state.bool_state  # use .string_state, .int_state, etc. for other types
print(current)  # prints the current value as a bool

# Modify the value at the same path.
stub.SetState(
    object_model_pb2.SetStateRequest(
        rules="meshing",
        path="/GlobalSettings/EnableCleanCAD",
        state=variant_pb2.Variant(bool_state=not current),
    ),
    metadata=metadata,
)

# Restore the original value.
stub.SetState(
    object_model_pb2.SetStateRequest(
        rules="meshing",
        path="/GlobalSettings/EnableCleanCAD",
        state=variant_pb2.Variant(bool_state=current),
    ),
    metadata=metadata,
)

Querying attributes

GetAttributeValue provides access to metadata, including constraints (range/min‑max, allowed/enumerated values), mutability (read-only/writable), availability (active/disabled), and default values.

Python

attribute_response = stub.GetAttributeValue(
    object_model_pb2.GetAttributeValueRequest(
        rules="meshing",
        path="/GlobalSettings/EnableCleanCAD",
        attribute="default",
    ),
    metadata=metadata,
)
print(attribute_response.result.bool_state)  # -> False

Executing commands

You can pass command arguments as a Variant map. ExecuteCommand executes the specified server-side command.

Python

stub.ExecuteCommand(
    object_model_pb2.ExecuteCommandRequest(
        rules="meshing",
        path="/",
        command="ImportGeometry",
        args=variant_pb2.Variant(
            variant_map_state=variant_pb2.VariantMap(
                item={"FileName": variant_pb2.Variant(string_state="mixing_elbow.pmdb")}
            )
        ),
    ),
    metadata=metadata,
)

Building command arguments incrementally

CreateCommandArguments creates a server-side argument object so you can set individual fields before calling ExecuteCommand.

Python

# Allocate an argument object on the server.
create_response = stub.CreateCommandArguments(
    object_model_pb2.CreateCommandArgumentsRequest(
        rules="meshing",
        path="/",
        command="ImportGeometry",
    ),
    metadata=metadata,
)
command_id = create_response.command_id

# ... populate fields via SetState using the command_id path ...

# Clean up without executing.
stub.DeleteCommandArguments(
    object_model_pb2.DeleteCommandArgumentsRequest(
        rules="meshing",
        path="/",
        command="ImportGeometry",
        command_id=command_id,
    ),
    metadata=metadata,
)

Subscribing to, streaming, and unsubscribing from events

SubscribeEvents registers interest in specific object model changes; StreamEvents delivers them as a server-streaming call; UnsubscribeEvents cancels the subscriptions when done.

Python

# Subscribe to modifications on a specific path.
subscribe_response = stub.SubscribeEvents(
    object_model_pb2.SubscribeEventsRequest(
        event_requests=[
            object_model_pb2.ObjectModelEventRequest(
                rules="meshing",
                modified_event_request=object_model_pb2.ModifiedEventRequest(
                    path="/GlobalSettings/EnableCleanCAD"
                ),
            )
        ]
    ),
    metadata=metadata,
)
tags = [r.tag for r in subscribe_response.responses]
# tags is a list of UUIDs — hold on to them; they are needed to unsubscribe.

# Stream events — events arrive only when something else modifies the
# subscribed path on the server (e.g. another client or a running solver).
stream = stub.StreamEvents(
    object_model_pb2.StreamEventsRequest(),
    metadata=metadata,
)
count = 0
for event in stream:
    mod = event.modified_event_response
    print(mod.path)   # -> '/GlobalSettings/EnableCleanCAD'
    print(mod.value)  # -> Variant carrying the updated value
    count += 1
    if count >= 3:
        break
stream.cancel()

# Unsubscribe.
unsubscribe_response = stub.UnsubscribeEvents(
    object_model_pb2.UnsubscribeEventsRequest(tags=tags),
    metadata=metadata,
)
for r in unsubscribe_response.responses:
    print(r.status)  # -> SUBSCRIPTION_STATUS_UNSUBSCRIBED

Streaming state changes

StreamStateChanges delivers a snapshot or diff of the object model whenever it changes. Use DIFF_STATE_FULL for a complete snapshot or DIFF_STATE_NOCOMMANDS for a lighter diff without command metadata.

Python

# Full snapshot on every change.
stream = stub.StreamStateChanges(
    object_model_pb2.StreamStateChangesRequest(
        rules="meshing",
        return_state_changes=True,
        diff_state=object_model_pb2.DIFF_STATE_FULL,
    ),
    metadata=metadata,
)
first_response = next(iter(stream))
stream.cancel()
print(list(first_response.deleted_paths))  # -> []  (empty list when nothing has been deleted)
print(list(first_response.events))         # -> []  (empty list when no events fired)

# Lighter diff without command metadata.
stream = stub.StreamStateChanges(
    object_model_pb2.StreamStateChangesRequest(
        rules="meshing",
        return_state_changes=True,
        diff_state=object_model_pb2.DIFF_STATE_NOCOMMANDS,
    ),
    metadata=metadata,
)
first_response = next(iter(stream))
stream.cancel()
assert hasattr(first_response, "state")

See ObjectModel for the complete reference material.